The Boston Christmas tree that adorns the Common every year travels all the way from Nova Scotia, and this year’s tree for Boston will arrive on Tuesday, Nov. 20.

The Christmas tree for Boston is a thank you gift from Nova Scotia — a visual representation of gratitude from the Canadian province for the aid Boston provided after the deadly Halifax explosion on Dec. 6, 1917.

On that day, two ships collided in Halifax Harbor, killing nearly 2,000 people “almost instantly,” injuring 9,000 more and leaving 20,000 homeless. As soon as they learned of the tragedy via telegram, Boston officials sent a slew of first responders to Nova Scotia and residents here raised $100,000 to help the Nova Scotia city rebuild (that’s more than $2 million in today’s money).

But that horrible day in Halifax history has lead to a heartwarming tradition with the yearly choosing-and-sending of the Boston Christmas tree.

“What was devastating to the province and in particular to Halifax has been able to become something of a celebration of the aftermath of that,” said Nova Scotia Deputy Premier Karen Casey. “We’re not forgetting the devastation and destruction and deaths, but we’re also [saying that] out of that destruction and desperation came something very positive.”

The bond between Nova Scotia and Boston is now something truly special, and that means it’s a big honor to play a part in the Boston Christmas tree tradition. Officials are always looking out for a satisfactory tree to send this way, said Tim Whynot of the Nova Scotia Department of Lands and Forestry, and sometimes people even submit their backyard trees for consideration.

Donating Boston Christmas Tree an honor for Nova Scotia residents

This year’s Boston Christmas tree is a 46-foot-tall white spruce from Oxford, Nova Scotia. A government staffer noticed the tree and officials reached out to the owners, Ross McKellar and Teresa Simpson, about donating it this holiday season.

"We are very proud and excited that our tree will represent Nova Scotia's gratitude toward the people of Boston," said Ross McKellar in a statement. "It is an honour for us to be part of this tradition of remembering our past and thanking Boston for their kindness, friendship and help during one of our province's darkest moments."

Whynot said that he’s never had anyone reject the idea of having their tree cut down to send to Boston. Most often, it means a chance to come here, as well, and see their tree — now the Boston Christmas tree — as it lights up for the first time.

Everything about the Boston Christmas tree is a celebration. When it was cut down on Thursday, Nova Scotia elementary school students were there with officials and the tree owners, waving Nova Scotia flags and enjoying hot chocolate and cookies. Before the tree heads to Boston, Nova Scotians send it off from Halifax with a Christmas parade.

The Boston Police Department will escort the official Boston Christmas Tree around 10 a.m. Tuesday, beginning in Billerica and continuing to Boston Common. Boston Parks Commissioner Chris Cook, an official Nova Scotian town crier, Santa Claus and local schoolchildren will greet the tree at its final destination near the Boston Visitors Center at 139 Tremont Street.

The Boston Christmas Tree Lighting celebration is on Thursday, Nov. 29 from 6 to 8 p.m. Casey will be down from Nova Scotia for that event, honoring the 101st anniversary of the explosion.

“I know Boston comes alive at that time and I’m really excited,” she said. “We want to personally say thanks to the folks in boston and I know people in Boston want to personally show their appreciation and their gratitude for the tree. It’s become symbolic of the whole bond between Halifax and Boston.”